EE strained his back while working overtime. EE was shoveling material under the #1 filter in R-55. He ended his shift at 11:00 p.m. He began to feel discomfort in the morning of 3/14 & went to emergency room he was given a prescription and was told to be off til 3/16. EE began his 7 days off (shift schedule) on 3/16 and was seen by the plant physician.